pinctrl: show pin name for pingroups in sysfs

Pin name is more useful to users.

After change, when cat pingroups in sysfs, it becomes:
root@freescale /sys/kernel/debug/pinctrl/20e0000.iomuxc$ cat pingroups
registered pin groups:
group: uart4grp-1
pin 219 (MX6Q_PAD_KEY_ROW0)
pin 218 (MX6Q_PAD_KEY_COL0)

group: usdhc4grp-1
pin 305 (MX6Q_PAD_SD4_CMD)
pin 306 (MX6Q_PAD_SD4_CLK)
pin 315 (MX6Q_PAD_SD4_DAT0)
pin 316 (MX6Q_PAD_SD4_DAT1)
pin 317 (MX6Q_PAD_SD4_DAT2)
pin 318 (MX6Q_PAD_SD4_DAT3)
pin 319 (MX6Q_PAD_SD4_DAT4)
pin 320 (MX6Q_PAD_SD4_DAT5)
pin 321 (MX6Q_PAD_SD4_DAT6)
pin 322 (MX6Q_PAD_SD4_DAT7)

Acked-by: Stephen Warren <swarren@wwwdotorg.org>
Signed-off-by: Dong Aisheng <dong.aisheng@linaro.org>
Signed-off-by: Linus Walleij <linus.walleij@linaro.org>

drivers/pinctrl/core.c

@@ -125,6 +125,25 @@ int pin_get_from_name(struct pinctrl_dev *pctldev, const char *name)
 	return -EINVAL;
 }
 
+/**
+ * pin_get_name_from_id() - look up a pin name from a pin id
+ * @pctldev: the pin control device to lookup the pin on
+ * @name: the name of the pin to look up
+ */
+const char *pin_get_name(struct pinctrl_dev *pctldev, const unsigned pin)
+{
+	const struct pin_desc *desc;
+
+	desc = pin_desc_get(pctldev, pin);
+	if (desc == NULL) {
+		dev_err(pctldev->dev, "failed to get pin(%d) name\n",
+			pin);
+		return NULL;
+	}
+
+	return desc->name;
+}
+
 /**
  * pin_is_valid() - check if pin exists on controller
  * @pctldev: the pin control device to check the pin on
@@ -1011,6 +1030,7 @@ static int pinctrl_groups_show(struct seq_file *s, void *what)
 		const unsigned *pins;
 		unsigned num_pins;
 		const char *gname = ops->get_group_name(pctldev, selector);
+		const char *pname;
 		int ret;
 		int i;
 
@@ -1020,10 +1040,14 @@ static int pinctrl_groups_show(struct seq_file *s, void *what)
 			seq_printf(s, "%s [ERROR GETTING PINS]\n",
 				   gname);
 		else {
-			seq_printf(s, "group: %s, pins = [ ", gname);
-			for (i = 0; i < num_pins; i++)
-				seq_printf(s, "%d ", pins[i]);
-			seq_puts(s, "]\n");
+			seq_printf(s, "group: %s\n", gname);
+			for (i = 0; i < num_pins; i++) {
+				pname = pin_get_name(pctldev, pins[i]);
+				if (WARN_ON(!pname))
+					return -EINVAL;
+				seq_printf(s, "pin %d (%s)\n", pins[i], pname);
+			}
+			seq_puts(s, "\n");
 		}
 		selector++;
 	}

drivers/pinctrl/core.h

@@ -148,6 +148,7 @@ struct pin_desc {
 
 struct pinctrl_dev *get_pinctrl_dev_from_devname(const char *dev_name);
 int pin_get_from_name(struct pinctrl_dev *pctldev, const char *name);
+const char *pin_get_name(struct pinctrl_dev *pctldev, const unsigned pin);
 int pinctrl_get_group_selector(struct pinctrl_dev *pctldev,
 			       const char *pin_group);